Serena Williams, of the United States, right, congratulates Bianca Andreescu, of Canada, after Andreescu won the women’s singles final of the U.S. Open tennis championships Saturday, Sept. 7, 2019, in New York. (AP Photo/Sarah Stier)

VIDEO: Andreescu beats Williams 6-3, 7-5 to become first Canadian U.S. Open singles champ

NEW YORK — Bianca Andreescu became the first Canadian to win a Grand Slam singles title, beating Serena Williams 6-3, 7-5 on Saturday in the U.S. Open women’s final.

The 19-year-old from Mississauga, Ont., used her powerful forehand — and was helped by an uncharacteristically bad service game from the veteran Williams — for her third tournament win of the season, and biggest by far of her career, in her first U.S. Open main draw appearance.

Andreescu converted on her third championship point of the match, breaking Williams with a forehand return before ecstatically sprawling belly-up on the court.

Then she got up, climbed a ladder to get to her players’ box and embraced coach Sylvain Bruneau.

Andreescu, seeded No. 15 at the major, will reach a career high No. 5 when the new WTA rankings are released Monday.

It wasn’t a pretty match for Williams, who struggled on her serve throughout, with her first-serve percentage dipping to 25 at one point in the second set.

But the 23-time Grand Slam champion showed fight late in the match. She staved off one championship point and erased a 5-1 deficit with consecutive breaks to tie the set 5-5 and send the crowd at Arthur Ashe Stadium into a frenzy.

The No. 8-seeded Williams won her first U.S. Open title here 20 years ago — before Andreescu was born.

While there was a loud applause from the crowd when Andreescu was introduced before the match, the ovation for Williams was deafening.

The Canadian broke Williams twice in the first set — in the first game and on a double fault to end the set — while facing just one break point, which Williams did not convert.

Williams double-faulted again to give Andreescu another break and a 2-0 lead to start the second set. The American responded by breaking Andreescu for the first time, but then lost her next serve as the Canadian built a 5-1 advantage.

Williams, whose disappointment was etched on her face during parts of the match, remains one short of tying Margaret Court’s record 24 Grand Slam titles.

She is also still looking for her first championship — major or otherwise — after returning from the birth of her daughter. Williams had won the 2017 Australian Open while pregnant and returned to the WTA tour at Indian Wells in March of 2018.

Saturday’s final was a rematch of last month’s Rogers Cup women’s championship in Toronto, which Andreescu won when Williams retired down 3-1 in the first set. That match lasted less than 20 minutes and gave Andreescu her second WTA victory of the season.

Andreescu approached a tearful Williams on the sideline that day in Toronto in a touching moment that led the American superstar to dub the young Canadian a ”great sportswoman.”

Andreescu was the first Canadian woman to play in a Grand Slam final since Eugenie Bouchard competed for the Wimbledon title in 2014.

Andreescu, who began the year ranked No. 152, reached a career high No. 15 heading into the U.S. Open after a stellar season that included her first two titles.

She has been one of the best Canadian sports stories of the year. She’s garnered praise from the likes of Wayne Gretzky, Sidney Crosby, Steve Nash, and Kia Nurse. Even Billie Jean King, whose name adorns the tennis centre where the U.S. Open is played, has tweeted about Andreescu multiple times.

She looked sluggish for parts of her 7-6, 7-5 semifinal victory against Switzerland’s Belinda Bencic Thursday night, but dug in and found another gear in the second set to rally back from deficits of 4-1 and 5-2.

Williams, on the other hand, looked otherworldly throughout the tournament, carving up opponents starting with Maria Sharapova in the first round. She also notched the quickest victory of the tournament, a 44-minute one-sided quarterfinal win over China’s Wang Qiang.